1. Field of the Invention
The present invention relates to devices for facilitating the removal of flange-topped rubber stoppers from installed positions within test tubes and like vessels.
2. DESCRIPTION OF THE PRIOR ART
So-called "anaerobic" tubes and flasks are heavy-duty Pyrex glass vessels that are used in the laboratory, and it is often necessary to plug the mouth of such a vessel to seal its pressurized contents, most commonly with a conventional rubber stopper that has a circular flange top for grasping, and a cylindrical lower portion for insertion within the vessel mouth. To ensure that the stopper is not dislodged by internal pressure, it is a common practice to apply a metallic retainer, such as an aluminum crimp seal that covers the stopper top and engages the underside of a lip that extends about the periphery of the top of the vessel. When experiments are completed and laboratory equipment set-ups are to be disassembled, the anaerobic vessels must be unplugged for cleaning and made available for reuse. This is typically accomplished by first removing the metal retainer by grasping the retainer's integral tear tab and then tearing it off so as to sever the hold of the retainer. Here, one must be cautious to avoid injury to the fingers by sharp metallic edges presented by the broken retainer. Then using both hands, the stopper flange is pried upwardly with the thumb to urge the stopper from the mouth of the vessel. All too often, a stopper will become stuck in place, and removal of such a stopper by hand will become a difficult, time-consuming task. Even when a stuck stopper is not encountered, the unplugging of several test tubes will often cause a bothersome soreness at the thumb tip, and sometimes tearing of the skin. At other times, particularly when there is difficulty in prying the stopper loose, the rim of the tube will break. Besides representing an equipment loss, jagged edges of a broken vessel and sometimes flying glass present an obvious immediate safety hazard to the handler. Such accidents can be particularly serious when toxic contents are involved.
Oftentimes test tube reactants will generate high-pressure gaseous by-products. In order to relieve this pressure prior to stopper removal, it is the prescribed practice to first pierce the stopper with a syringe to relieve the pressure. Unfortunately, through human error and oversight, occasionally some vessels will not be depressurized. In such cases, unplugging of the vessels will be occasioned by expelling of the liquid and gaseous contents. In some cases, when the metal retainer is removed, the unrestrained stopper will immediately be forcefully propelled from the vessel, followed by the pressurized contents. This can also be particularly hazardous when the contents are harmful substances.